Herbaceous Peat Enhances Nitrogen Retention via Microbial Regulation in Chicken Manure Composting
Description
Aerobic composting is an effective technology for resource utilization of chicken manure, yet severe reactive nitrogen emissions (NH3 and N2O) during composting lead to significant nitrogen loss and secondary environmental pollution. Natural or semi-processed additives have emerged as promising materials for nitrogen retention and reduction of nitrogen emissions in composting process. In contrast, the systematic comparison of nitrogen retention efficiency and the differentiated microbial regulatory mechanisms of light calcium carbonate (LCC), oyster shell powder (OSP), and herbaceous peat (HP) in chicken manure composting remains unclear. In this study, a composting experiment with chicken manure and wheat straw was conducted, with 5% LCC, OSP, or HP added. Results showed that all three additives effectively optimized composting physicochemical microenvironment, indicating the compost reached a mature state without phytotoxicity. Among them, HP exhibited the greatest reductions in cumulative NH3 and N2O emissions, by 27.23% and 36.03%, respectively, compared with CK, followed by OSP and LCC. All additives inhibited the expression of nitrogen-cycling functional genes, with OSP and HP showing greater suppression of nitrification genes (AOA-amoA, AOB-amoA), and LCC exerting the strongest inhibitory effect on denitrification genes (nirK, nosZⅠ). HP had the most complex bacterial co-occurrence network and balanced fungal interspecific competition and cooperation, while LCC enriched aerobic functional bacteria and OSP adapted to alkali-tolerant microorganisms. The regulatory mechanisms of the three additives for nitrogen retention were distinct: LCC improved compost aeration to inhibit anaerobic denitrification; OSP regulated pH and adsorbed NH4+-N; and HP achieved stage-specific synergistic regulation of the nitrogen cycle through the dual advantages of humic components and a porous structure. This study clarifies the effects of nitrogen retention and microbial mechanisms of LCC, OSP, and HP in chicken manure composting, and provides theoretical insights and technical guidance for selecting and applying efficient, sustainable natural additives in livestock manure composting.
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Institutions
- Nanjing University of Information Science and TechnologyJiangsu, Nanjing